Honestly speaking there is no big deal in writing a book. In fact anyone in cabin crew can write a book. There are so many interesting and funny stories that happened in the skies,overseas etc that could be recorded in a book. If the publisher don't approach you, you may publish your book at your own expense. The only difference is whether you can recover your cost or not. If the publisher does it on your behalf then you don't even have to dish out a cent.
Not necessary to have stories from the air. I am sure there are many interesting stories in your work place,schools, home etc which you may tell in a book.
There was a taxi driver in S'pore who wrote a book about his daily encounter with his passengers. He was a PhD graduate from Stanford university but was retrenched from his post as a lecturer. His book was a big hit here. See, you can also write like him or me.
Better still if you want to co-write with me (for my second book) you are most welcome. Please email me and we can together embark on a writing project.